title: Drug delivery to the ocular posterior segment using lipid emulsion via eye drop administration: effect of emulsion formulations and surface modification.
abstract: This work explored submicron-sized lipid emulsion as potential carriers for intraocular drug delivery to the posterior segment via eye drops. The effects of physicochemical properties of lipid emulsion on drug delivery were evaluated in vivo using mice. Different formulations of submicron-sized lipid emulsions were prepared using a high pressure homogenization system. Using coumairn-6 as a model drug and fluorescent marker, fluorescence could be observed in the retina after administration of the lipid emulsion. The fluorescence intensity observed after administration of medium chain triglycerides containing the same amount of coumarin-6 was much lower than that observed after administration of lipid emulsions. The inner oil property and phospholipid emulsifier did not affect the drug delivery efficiency to the retina. However, compared with unmodified emulsions, the fluorescence intensity in the retina increased by surface modification using a positive charge inducer and the functional polymers chitosan (CS) and poloxamer 407 (P407). CS-modified lipid emulsions could be electrostatically interacted with the eye surface. By its adhesive property, poloxamer 407, a surface modifier, possibly increased the lipid emulsion retention time on the eye surface. In conclusion, we suggested that surface-modified lipid emulsions could be promising vehicles of hydrophobic drug delivery to the ocular posterior segment.
authors.affiliation: Laboratory of Pharmaceutical Engineering, Gifu Pharmaceutical University, 1-25-4 Daigaku-Nishi, Gifu 501-1196, Japan.
authors.forename: Lin
authors.initials: L
authors.lastname: Ying
authors.forename: Kohei
authors.initials: K
authors.lastname: Tahara
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Takeuchi
mesh_terms: D060433:Administration, Ophthalmic; D000818:Animals; D021461:Animals, Outbred Strains; D002626:Chemistry, Pharmaceutical; D048271:Chitosan / Q000737:chemistry; D003374:Coumarins / Q000008:administration & dosage / Q000737:chemistry; D004655:Emulsions / Q000737:chemistry*; D008055:Lipids / Q000737:chemistry*; D008297:Male; D051379:Mice; D009883:Ophthalmic Solutions / Q000737:chemistry*; D020442:Poloxamer / Q000737:chemistry; D012160:Retina / Q000378:metabolism; D013499:Surface Properties; D013844:Thiazoles / Q000008:administration & dosage / Q000737:chemistry
chemical_list: D003374:Coumarins; D004655:Emulsions; D008055:Lipids; D009883:Ophthalmic Solutions; D013844:Thiazoles; C517282:coumarin 6; D020442:Poloxamer; D048271:Chitosan
keywords: Lipid emulsion; Posterior segment; Retina; Surface modification; Topical administration